Interesting, I really was curious as to specific caliber. Flayderman's book says "38 Colt and 41 Colt calibers; 38 S&W made in lesser quantities." The right side of the barrel only says COLT. D.A. 38. I don't know one from the other but a 38 special slips in the cylinder. I dont have any 38 colts laying around. Not that I have any intention of firing this gun as it isn't mine. Thanks